Two introductions (khrid yig) to Dzogchen practice (Kloṅ chen sñiṅ thig gi sṅon 'gro'i khrid yig thar lam gsal byed sgron me and 'Od gsal rdzogs pa chen po yaṅ gsaṅ bla na med pa spyi'i khyad par gyi khrid yig lam bzaṅ ye śes sñiṅ po)